Conventionally, with regard to a motor driving apparatus for use in a dishwasher, it is required to reduce the size of a pump motor by employing a sensorless brushless motor driven by an inverter (see, for example, Japanese Patent Laid-open Application No. 2003-190070).
In the above configuration, however, since a motor induced voltage should be obtained for the detection of a position of a rotor, a motor driving method such as a rectangular wave driving may be employed. As a result, there has been a problem that waveform distortion of a motor current and a noise of the motor are increased.
On the other hand, if a motor is driven not on a sensorless driving method but on the basis of a position sensor signal, a position sensor has to be installed within the motor, which would result in an increase in both the thickness and the price of the motor, while deteriorating the reliability thereof.